<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>应用算术运算符计算商品金额</title>
<script type="text/javascript">
      var price=19.7;     //定义商品单价
      var number=100;     //定义商品数量
      var sum=price*number;  //计算
      window.alert(sum);
      document.write("<h1>This is a heading</h1>");
</script>
</head>
<body>

</body>
</html>